The control of fluid introduction into and out of body conduits such as vessels, is of great concern in medicine. As the development of more particular treatments to vessels and organs continues it is apparent that controlled introduction and removal of fluids is necessary. Fluid delivery and removal from such sites, usually referred to as irrigation and aspiration, using fluid exchange devices that control also need to be considerate of potential volume and/or pressure in the vessel or organ are described together with catheter and lumen configurations to achieve the fluid exchange. The devices include several electrically or mechanically controlled embodiments and produce both controlled and localized flow with defined volume exchange ratios for fluid management. The applications in medicine include diagnostic, therapeutic, imaging, and uses for the introduction or removal of concentrations of emboli within body cavities.

The devices and related methods of the invention relate to the controlled introduction and removal of fluids in diagnostic, therapeutic and imaging applications within the body. Specifically, the invention relates to the advantageous use of a fluid exchange device in combination with a catheter to produce a system for controlled aspiration and irrigation and the selective and localized exchange of fluids within a body conduit, for example, in the diseased region of a blood vessel having a blockage or lesion. The devices of the invention, and the methods enabled by the use of the devices, have several different components that can be used individually or integrated into a system for use within an organ and within the vasculature of the body where controlled and localized irrigation and aspiration are performed together as a therapeutic procedure or in tandem with a separate therapeutic procedure.
Irrigation and aspiration are clinically important in many surgical procedures when fluids are selectively introduced into and removed from a target site within the body, usually while a surgery or other therapeutic medical procedure is performed. When the site of the therapeutic treatment is inside a body cavity or in the vasculature of the body, such as in a blood vessel, the irrigation and aspiration functions require special apparatus and methods. Surgical and percutaneous systems that both irrigate and aspirate have been developed, and some of these systems are catheter-based such that the introduction and removal of fluids is performed within an organ or a vessel by using the catheter as the conduit to introduce and remove fluids from a target site. As will be readily appreciated, the catheter allows the control elements to be remotely located, e.g., outside the body while the actual irrigation and aspiration functions are selectively provided within the body by selectively orienting the distal end of the catheter to the target site. In such cases, as is the case in open surgeries, the irrigation and aspiration functions accompany a therapeutic procedure that is performed at the target site along with the irrigation and aspiration.
Catheter-based irrigation and aspiration systems are unique in many respects due to their use in clinical situations where blockages or lesions exist inside a blood vessel, such as a coronary or carotid artery, and dangers arise from the creation and release of emboli within the vessel. In many intravessel therapeutic procedures, the danger from the creation of emboli is an unavoidable aspect of the therapeutic procedure. For example, lesions of atherosclerotic plaques inside a blood vessel are treated by several therapeutic procedures including endarterectomy, atherectomy, the placement of intravessel stents, balloon angioplasty, surgical ablation of the lesion, thrombectomy, OCT, dialysis shunt clearing and others. However, while each of these procedures has great therapeutic value in treating the lesion, each carries the risk of creating emboli during the procedure. As with any procedure conducted in the cardiovascular system, the risk is particularly great where plaque dislodged from inside a blood vessel can travel to the brain causing serious brain injury or death. For example, treating lesions of the carotids necessarily involve high risk. Currently, carotid treatments are attempted together with deployment of a filter to attempt to track emboli generated by or released from a carotid lesion. Unfortunately, crossing a carotid lesion with a filter or other structure can generate a cerebral ischemia or stroke. Schlueter et al. 2001, Circulation 104 (17) II-368. Moreover, studies have shown that merely crossing a carotid lesion with a guide wire can generate emboli. Al-Mubarak et al.: Circulation 2001 OCT 23:104 (17): 1999-2002. Also, some lesions carry such a high risk of generating emboli that therapeutic treatments are attempted only in the most severe cases. Where a chronic total occlusion exists, the diagnosis is particularly poor because it is impossible to place a structure distal of the occlusion such that emboli generated by the removal of the occlusion can be captured before circulating in the bloodstream. Such occlusions can only be treated by removing the occlusion from the proximal side, where emboli removal is uniquely difficult. Accordingly, if the capability existed to dramatically reduce the dangers of emboli creation during therapeutic procedures inside a vessel or organ of the body, the existing procedures would be safer and more widely practiced, and new procedures would be performed.
A variety of systems to contain and remove emboli have been proposed wherein a portion of a vessel that contains a lesion is segregated by two occluding members, typically two balloons, which are inflated proximate and distal to the lesion to effectively seal the inside of a region of the vessel containing a lesion prior to treatment of the lesion. Once treatment is complete, embolic particles such as dislodged plaque are removed by applying suction between the balloons. However, the tissue affected by a lesion is notoriously delicate and the treatment of the lesion has the capability to generate or release emboli whenever any mechanical manipulation of the lesion occurs. The generation and/or release of emboli is a concern virtually anytime a structure is passed through a susceptible vessel. Such circumstances include the placement of a balloon or stent, the placement of a filter, or simply the use of a catheter or guide wire for imaging, diagnostic, or any other procedure. In many procedures, the internal portion of a vessel is occluded to provide a segregated region of a vessel through which fluid does not flow. Moreover, virtually anytime structures are inserted into the vessel, the generation of release of emboli is a concern. For example, in the common practice of placing a stent inside an artery, a filter may be placed distally of the stent to attempt to collect emboli generated when the stent is expanded to engage plaques or lesions inside the vessel. All devices placed distal involve the crossing of the lesion. All crossings of lesions create emboli of some quantity and significance. Such systems cannot protect the patient against the potential harm inherent in the placing the device. Additionally, once the stent is in place, the filter must be removed by pulling it through the portion of the vessel in which the stent has been inserted. This carries the risk that the filter will impact the vessel and cause the release of emboli and/or contact the stent and either displace the stent or similarly cause the release of embolic particles. The use of occluding members of any type has certain drawbacks. Anytime a structure is used as an occlusive member inside a vessel, the structure must deform the vessel from the inside to create a seal about the periphery thereof with the internal surface of the vessel. For example, to make the seal tight enough to prevent the passage of fluid and emboli past the balloon, the expansion of the balloon typically deforms the vessel outward and may disrupt plaque in and about the point of contact between the vessel and the balloon. Moreover, any plaque that becomes dislodged outside the barrier formed by the balloon is released into the blood stream because there is no mechanism distal of the balloon to remove the emboli. For this reason, irrigation and aspiration proximate to the lesion are particularly important.
To create a segregated region of a vessel, a two-balloon system may be used. However, certain disadvantages of a two-balloon system also arise from the placement of balloons on both sides of a lesion and the nature of the blood flow that occurs in the region of the vessel containing the lesion once the balloon is removed. At the point of contact between the balloon and the vessel, plaque may be compressed underneath the balloon and may become dislodged upon reestablishment of flow through the vessel. Furthermore, many clinicians have observed that the region distal of a lesion is more likely to exhibit plaque formation than the region proximal of a lesion. Thus, the use of an occluding member distal of a lesion does not eliminate the risk of creating emboli that may enter the vessel. The risk is particularly great when a second balloon is used because the balloon is not advantageously placed for the removal of emboli created by the use of the balloon itself and because the balloon must be removed by passing it across the lesion upon completion of a procedure. This drawback is present in all circumstances when a balloon is advanced across a lesion because, when any occluding member is placed distally of the lesion, the occluding member must be drawn back across the lesion to remove the occluding member at the end of a procedure. Each passage of an occluding member across the lesion, even in a retracted or deflated state, carries a substantial risk that additional emboli will be produced.
Also, the placement of two balloons requires additional time to inflate the second balloon and adds to the complexity of a device due to an additional lumen that must be incorporated into the catheter to inflate the balloon. In a finite number of cases, the occluding member that is distal of a lesion, and is required to retain emboli in a defined area within the vessel, has been observed to fail, thereby releasing the emboli into the bloodstream. Because the second balloon is relied upon to prevent the flow of emboli past the region of the vessel containing the lesion, the failure of the balloon is a critical event that threatens the health of a patient undergoing the procedure. Furthermore, due to geometric constraints, the second balloon often acts as the guide wire as well. When delivering tools to perform the therapeutic or diagnostic procedure within the vessel, the balloon may move and disrupt the vessel wall. Introduction of tools and other manipulations of a distally located balloon can also result in deflating the balloon or otherwise causing the balloon to lose patency on the interior of the vessel.
Anytime that a balloon is placed distal to a lesion, the contact between the balloon and the lesion carries the risk of damaging the vessel. For these reasons, the use of balloons inside the vessel is preferred to be minimized and the length of time and extent of contact between a balloon and the inside of a vessel should be reduced. Ideally, the balloon or other occluding member could be placed proximal to a lesion so that the area containing the lesion would be isolated. To achieve this, the irrigation and aspiration functions would have to be provided by a structure that is positioned distal of the occluding element, such that the occluding element could be placed proximal of the lesion, and the aspiration and irrigation functions achieved distal of the occluding member.
Even under existing technologies where aspiration and irrigation are applied in a catheter based system, the parameters of fluid flow, as well as the placement of the aspiration and irrigation ports relative to an occluding member, are important to the physiological outcome for any given procedure. For example, removal of fluid and/or embolic particles by simple suction from within a body conduit may only remove a portion of the fluid present in the vessel and may leave emboli in place even if all of the fluid is removed and replaced. Deposits of plaque and other debris that may exist inside a vessel have a tendency to adhere to one another and particulate emboli tend to adhere to the sidewalls of the vessel. Thus, a system that provides limited fluid exchange is particularly unlikely to achieve a complete removal of emboli. Also, given that the interior walls of a vessel may have been contacted from within during a therapeutic procedure, a high likelihood exists that additional particles may be dislodged upon the establishment of a robust fluid flow through the vessel.
Ideally, a system for aspirating and irrigating the interior or a vessel or organ would provide both fluid exchange and fluid flow parameters that are at least similar to that experienced during ordinary physiological functions and preferably would create a turbulent fluid flow that would proactively assist in the removal of particles and other emboli. Such a system would require both a catheter element that achieved aspiration and irrigation as well as a fluid exchange apparatus that would be coupled with the catheter to produce the desired fluid flow rates and other fluid parameters. Because of the wide variation in intravessel procedures and the location of disease, an irrigation and aspiration system would also be particularly useful if the catheter element could be selectively positioned along a specified length of a vessel where emboli may be created together with operation of the fluid exchange apparatus to control the irrigation and aspiration flow. This capability in the catheter element is most readily created with only a single balloon system having a separate, movable, irrigation and aspiration catheter.
In the prior art two-balloon system described above, where a region of a vessel is segregated by a pair of balloons located both proximally and distally of a lesion, the area of fluid flow is limited to the region defined by the placement of the two balloons. The problem is particularly acute when a vessel is treated with a procedure that installs a stent or manipulates the plaque in a vessel, such as with an angioplasty, where the lesion is physically manipulated as part of the therapeutic treatment. Assuming that the therapeutic treatment is successful, the vessel is treated by virtue of expanding the interior volume and promoting the flow of blood through the vessel. Under these circumstances, the portions of the vessel distal of the lesion have been contacted by a balloon and are then exposed to a higher volume of fluid flow than existed before the procedure. In the context of a typical patient, a vessel which had become slowly blocked due to the deposit of plaque over a large number of years has been expanded by the treatment of the lesion and this therapeutic treatment at an upstream point subjects the region in which the lesion is located and those downstream internal portions to a rate and volume of blood flow that has not been experienced in the many years since the vessel began to become occluded. Under these circumstances, an additional risk exists that plaques located downstream from the lesion will be dislodged and will enter the circulation causing serious injury.
As with ordinary irrigation and aspiration in an open surgery, the irrigation and aspiration that are applied through existing catheter systems are typically regulated only by setting the positive or negative pressure that is applied to the aspiration or irrigation lumen of the catheter and is in turn communicated to the distal end of the catheter to insert or remove fluid respectively. However, to create the specific fluid flow parameters that maximize the removal of emboli and the fluid displacement within a vessel, thereby establishing fluid change in the vessel in the most physiologically relevant manner, a specialized fluid exchange device would have to be created to regulate the fluid flow parameters of both the irrigation and aspiration functions of the system.
An ideal irrigation and aspiration system could be an additive component to several other apparatus that are used in therapeutic, diagnostic, or imaging applications in the body such that the capability of the system would not be exclusive of other technologies that have been applied to enhance the safety of an intravessel procedure. Several different approaches apart from irrigation and aspiration have been attempted to physically capture emboli downstream at a lesion, most notably through the use of filters. However, filters have inherent drawbacks that cannot be completely eliminated. For example, embolic particles smaller than the filter pore size, commonly on the order of 100 microns evade filters, which must not be so small that physiologically important elements such as red and white blood cells are captured by the filter. Also, particles larger than the pore size tend to become trapped in the filter such that the filter itself becomes an occlusive element and blood flow through the filter is impeded. Also, as described above for occluding structures, whenever a filter is introduced distally to the lesion in a vessel, a finite probability exists that the removal of the filter will generate emboli. Still further, where a stent is placed at a lesion, the movement of the filter past the stent and through the vessel has the capability to catch or displace the stent.
Although certain portions of the discussion herein are directed towards a preferred embodiment of the apparatus of the invention used in an intravessel procedure, the devices and methodologies of the invention can readily be applied to non-vessel sites within the body such as within any body conduit such as an ear canal, colon, intestine, the trachea, lung passages, sinus cartilages, or any internal volume wherein a controlled and localized irrigation and aspiration function are desired. For example, in a diagnostic colonoscopy an endoscope may be introduced to aid in optical visualization of the site. However, the colon responds to fluid pressure changes and thus while trying to clear the field the tissue of note may move. To aid in this diagnostic situation, a controlled introduction of a clear fluid could be introduced in concert with an equivalent aspiration of dirty fluid. As such, the tissue may remain in the field of view while the process occurs. For imaging purposes the introduction of a contrast agent while simultaneously extracting an equivalent fluid will allow a vessel or organ to maintain its normal fluid level and pressure. As the imaging is completed, the same system could then return a more normal fluid to the site while extracting the foreign contrast agent. Imaging xe2x80x9cpig-tailxe2x80x9d catheters are presently used to introduce contrast agents to vascular system, even though radiopaque contrast agents are known to maintain a level of toxicity (Solomon, Kidney International, 1998, vol. 53, pp. 230-242). If the field of contrast was introduced and extracted as proposed by Courtney, et al., the patient""s exposure would be substantially reduced.
The present invention provides control of both irrigation and aspiration functions at a selected location within a body cavity or conduit, such as a target region of a blood vessel. The region of the vessel to which an irrigation and aspiration function are provided may include both a therapeutic treatment site, the site proximal to the placement of a balloon, or a length of a vessel both proximal to and distal of a lesion wherein a surgical treatment was performed, where a diagnostic or therapeutic procedure caused the insertion of a dye or other solution, such as a clot dissolver, or where a total chronic occlusion occurs. Because the irrigation and aspiration functions are performed simultaneously, the fluid exchange apparatus of the invention is able to simultaneously regulate both irrigation and aspiration in a manner that advantageously controls the fluid flow rates and fluid flow parameters. This capability can be achieved both by controlling the flow rates using an electronic control system, as well as providing a mechanical apparatus that controls irrigation and aspiration flows when actuated by a user. When the catheter and fluid exchange device are combined into the system of the invention, the combination provides unique capabilities for treating or diagnosing a lesion contained within a vessel. For example, the lesion may be pre-treated prior to the therapeutic treatment which typically comprises ablation of a lesion or placement of a stent or expansion of the diameter of the vessel, i.e., through an angioplasty procedure. In a diagnostic embodiment, dye or other diagnostic markers can be infused distally of the occluding member and proximate to the lesion while avoiding the potential hazards of passing a collapsed balloon across the lesion. This provides a diagnostic capability which has substantially reduced risk relative to a therapeutic treatment that requires expansion of an occluding member distal of the lesion. Because of the added safety margin, the diagnostic procedures can be more readily performed without the risk of producing emboli and thus are a more available complement to the therapeutic procedure.
Preferably, the system of the invention includes a catheter element having specific features designed to facilitate the desirable fluid flow parameters when connected to the fluid exchange apparatus. Ideally, when coupled with an apparatus that inherently provides controlled and regulated fluid flows for both aspiration and irrigation, the catheter works in tandem with the apparatus to create both controlled and localized irrigation and aspiration through a catheter-based system. For example, the apparatus of the invention allow the user to control the irrigation and aspiration flow volumes, and by virtue of a specially designed catheter system, provide improved fluid flow parameters that facilitate quantitative volume exchange within a vessel or other cavity and produce defined fluid flow parameters in a region bordered by an occluding element. Accordingly, the aspiration and irrigation functions provided by the fluid exchange device can be added to several existing devices such as balloon occluding elements or filters, or can be used alone as a catheter-based fluid exchange system without any additional device. Thus, the fluid exchange capabilities can be added to an existing device such as a straight catheter or filter, or an existing device can be integrated into the remaining components of the present invention to provide the advantageous irrigation and aspiration functions as described herein. For example, to decrease time during a therapeutic or diagnostic procedure, the portion of the catheter element providing the irrigation function could be combined with a catheter used to perform an angioplasty procedure.
When so integrated, the irrigation and aspiration functions of the invention are located distal to the angioplasty balloon and the enhanced removal of emboli is facilitated. Also, the location of the irrigation and aspiration lumens can occur such that the aspiration ports are on opposite sides of an occluding member or other structure such that a direct irrigant to aspirant volume exchange may or may not occur in the lesion of a vessel. In preferred embodiments of the system of the invention, the catheter element provides turbulent, rather than laminar, flow within the vessel. Turbulence is introduced locally at the region of fluid exchange within the body. In a turbulent flow, the velocity at a point fluctuates at random with high frequency and mixing of the fluid is much more intense than in a laminar flow. Turbulent flow is specifically preferred because it reaches the walls of a body structure and facilitates both fluid exchange and dislodging of particulate matter. To reach the walls, the irrigation ports exit the catheter element in the direction of the wall. To accomplish this, the catheter element preferably has ports that exit orthogonal to the wall of the distal end of the irrigation lumen of the catheter. The aspiration lumen may establish a local laminar flow profile. This results in laminar flow about the vessel.
Also, in a turbulent flow, the velocity at a point fluctuates at random with high frequency and mixing of the fluid is much more intense than in a laminar flow. This is of particular value when attempting to clear any site of debris. Without turbulence, the flow along the sides of a vessel/lumen is approximately 0. When trying to remove/clear or exchange fluids thoroughly is it imperative to facilitate mixing. Mixing can only reach the vessel walls through the application of turbulence. This is appreciated by the vessels as well, since turbulence can be achieved with this invention without high-powered injection systems that carry physiological risks associated with their inherent power and abnormally high flow rates.
In more scientific terms, when a laminar flow is made turbulent, then the velocity will become more uniform and higher, and as a result, fluid particles in the boundary layer can move farther downstream before separation takes place. This turbulence is generally local to the irrigation area and controlled by the dimensions and orientation of the ports of the irrigation lumen.
The flow and velocity exchange rate through the entire system is not altered significantly since the turbulence is local area around the irrigation ports. But turbulence for an equivalent flow produces a much more uniform flow across the vessel. This results in higher velocities along the wall where emboli and thrombus are known to be in residence. From a physiological relevance standpoint, blood clots, or thrombi, are much more likely to be released into turbulent than in laminar flow. (Berne and Levy, 2001, Cardiovascular Physiology, p. 126).
Because flow is proportional to viscosity, irrigation with any number of fluids can increase the flow over just aspiration of the site. For example, the viscosity of blood is 5 times that of water in a vessel larger than 0.3 mm in diameter, (from graph 5-14, in Berne and Levy, p. 129). The resulting combination of turbulence and the introduction of various fluids allows for substantially variable fluid flows which cannot be achieved without the combination herein disclosed.
Those of skill in the art will appreciate that the fluid exchange capabilities and fluid flow parameters provided by the invention can be integrated into a number of systems to provide irrigation and aspiration and essentially any physiological context where near quantitative removal of fluid or particles from a site is desired. As noted above, the enhanced fluid flow parameters can be strategically oriented relative to the placement of an occluding member, such as a balloon, to effectively remove fluids or solid matter either proximal to or distal of the occluding device. The catheter element of the apparatus can also be positioned to facilitate the removal of dyes, or therapeutic or diagnostic compounds as part of the fluid exchange function of the apparatus of the invention.
In a preferred embodiment, the invention provides both irrigation and aspiration in a selected region of a vessel proximate to a lesion, but without any occlusion distal of the lesion such that the occluding element may be both inserted and removed without passing across the lesion. Because of the design of the catheter-based system, a single catheter element may both aspirate and irrigate and may be moved within the vessel whether or not used in combination with other apparatus. When used in combination with an occluding element, the irrigation and aspiration factors may be fixed in place proximate to a lesion within a vessel or may be movable such that a single catheter element having both aspiration and irrigation functions can be advanced into an area proximate a lesion and actuated to perform the irrigation and aspiration function both proximate to the lesion and distal to the occlusion element. Similarly, if there exists a distal device (filter or occlusion balloon) this system can be activated to accomplish the following optimum clinical benefit. The irrigation ports being just proximal, but not exclusively proximal, to the aspiration port, then the vessel can be irrigated actively with the local flow moving prograde. This drives the emboli up against a more distal occluder/filter and there the aspiration port evacuates the emboli. Used in concert with existing filters or balloons this results in optimum retrieval of emboli from the active irrigation. This embodiment does not require a proximal occlusion for clinical benefit.
In procedures where emboli may be present, this device may be used as part of a method to extract the emboli generated during either a therapeutic, surgical, imaging or diagnostic procedure. The volume exchange provided by the current invention is also adapted to facilitate removal of fluids within a measured portion of a vessel where vessel dimensions and fluid volumes are known. This device affords a simple mechanical means through which these may occur in concert. Primary applications have been identified that produce a 1:1 exchange of fluids, but further applications include pulsatile exchange rates and ratios other than 1:1.
The control aspect of the invention is derived in part from measured volumes that may be inserted and removed through a catheter system comprising an irrigation lumen and an aspiration lumen in fluid communication with irrigation and aspiration port(s) that insert and remove a defined or predetermined volume of solution. The design of the catheter and the fluid flow parameters achieved at the target site produce specific fluid dynamics within a vessel or body conduit that promote the removal of emboli and/or the near quantitative removal of a fluid contained in the region of a body conduit. In a preferred embodiment, a catheter coupled to a fluid exchange apparatus is actuated to create turbulence within the vessel or organ and proximate to the ports or exit holes of the irrigation lumen. As described in detail below, the size and orientation of the ports and lumen changes the fluid flow parameters such that defined flow rates, volumes, vortices, turbulence and ratios of fluids exchanged within the body can be custom designed for any application, vessel, or organ, as well as for specific diagnostic, therapeutic or imaging applications. Because many of the embodiments of the invention are used within the cardiovascular system, the irrigation and aspiration function can be designed such that fluids move into the vasculature in a pulsatile manner as with the movement of blood within the vessel caused by the beating heart. This type of fluid movement and fluid exchange provided by the aspiration and irrigation functions of the invention is advantageous because the insertion and removal of fluid in this manner exposes the vessels or other structures to fluid flow that is physiologically relevant. In the sense that the vessel experiences fluid flow that is similar to that experienced after the therapeutic, diagnostic, or imaging procedure is performed and any emboli that would be released following the procedure are more likely to be released during the irrigation or aspiration process performed by the devices of the invention.
As described in more detail below, the design also facilitates a defined fluid exchange rate, such as 1:1 volume exchange that avoids damage to the vessel while producing turbulence to facilitate the removal of emboli. Generally, turbulent flows provided by the device of the invention are localized and controlled in both volume and location and are typically higher than that provided by the existing devices in terms of both flow and velocity. Target flows of 1 cc/sec are relevant to vessels such as the vein grafts, flows up to 2 cc/sec are relevant for vessels such as the carotids. (Louagie et al., 1994, Thorac Cardiovasc Surg 42(3):175-81; Ascher et al., 2002, J Vasc Surg 35(3):439-44).
As noted above, an advantage of the invention is the generation of localized turbulence in the vicinity of the infusion catheter such that volume exchange within the vessel promotes the disruption of embolic particles that are only loosely attached to the interior walls of a vessel. This advantage is derived from both the design of the catheter, which affects the location in which fluids are inserted and removed into a vessel or an organ, as well as the specific design and function of the fluid exchange apparatus that, when coupled with the catheter of the invention, combine to produce improved fluid exchange and fluid flow parameters. For example, in an ordinary vessel that is roughly cylindrical within a defined axial distance along the length of a vessel, the removal of liquid generally produces a laminar flow through the center of the annular structure of the vessel and the fluid along the walls of the vessel are largely left in place. With a turbulent fluid flow profile, the fluid introduced into the vessel causes an exchange between the irrigant the existing fluid that is localized along the vessel walls and generally causes a more thorough mixing of the fluids within the vessel such that a more complete fluid volume exchange occurs and the removal of embolic particles is enhanced.
Although the particular parameters vary according to the designs described below, the fluid exchange achieved by the fluid exchange apparatus and the irrigation/aspiration catheter results in an insertion and removal of a defined volume within a vessel. As described in further detail below, the overall system is comprised of a fluid exchange apparatus that may have a mechanical or electrical, or both, fluid exchange component that converts a defined volume of fluid exchange with a defined axial movement of the catheter such that the volume of fluid exchanged per measure of distance of axial movement of the catheter through a vessel is known. Preferred embodiments of the fluid exchange apparatus are a substantially closed system wherein a reservoir containing irrigating fluid is combined with a reservoir containing the aspirated fluid such that known volumes are exchanged through a system that is essentially xe2x80x9cclosedxe2x80x9d except for the exchange site within the vessel. The terms xe2x80x9csubstantially closedxe2x80x9d mean that the system is closed because the volume of fluid inserted as irrigant solution is removed as aspirant solution in a predetermined ratio and any deviance from the ratio is attributed to only a volume of solution that is retained within the body at the target exchange site. For example, when a system of the invention is applied to irrigate and aspirate fluid from within a vessel, the system is substantially closed because the only difference between the fluid inserted as irrigant and removed as aspirant is that which is purposefully left behind in the vessel. When the volume exchange ratio of the device is set at a 1:1 ratio, the volumetric exchange of fluids is very near to equivalent. The fluid exchange apparatus may also be actuated in such a manner that the flow produced by actuating the fluid exchange apparatus is a defined increment. Thus, a known volume of fluid is exchanged at the target site and the clinician knows with certainty the volume of irrigant fluid that is inserted as well as the volume of fluid that is aspirated out of the target site.
In one embodiment, the device of the invention provides a 1:1 ratio of irrigation to aspiration fluid exchange such that the volume of fluid introduced to a vessel or organ is exactly matched by the volume removed. Through control of the location and movement of the device of the invention, the interior of a vessel or organ can undergo a complete fluid exchange by advancing the infusion catheter along the length of a vessel where removal of fluid is desired. By this process, several results are achieved that are beneficial therapeutically. First, the vessel experiences a turbulence and a fluid flow that is physiologically relevant in the sense that both the volume of fluid moving across a vessel as well as the turbulence are similar to the parameters that the vessel would experience under blood pressure. This similarity has several aspects. First, the turbulence that occurs in a vessel is similar to the turbulence caused by the motion of blood moved by a beating heart. Second, the pulsatile nature of the fluid exchange is also similar to the varying pressures and pressure profile caused by ventricular contraction and the ordinary movement of blood throughout the arterial system. Finally, these specific fluid flow characteristics are achieved without producing substantially increased pressures within a vessel and without distending the vessel through the application of increased fluid pressures. Thus, the combined irrigation and aspiration of controlled volumes of liquid treat the vessel with a physiologically relevant fluid profile.
Because the device of the invention offers the ability to introduce and remove a defined volume of fluid, the clinician can have a high degree of certainty that the entire internal volume of a region of a vessel has been rinsed with an irrigation fluid by knowing the approximate internal volume of the vessel and the length of the vessel in which irrigation and aspiration are performed. For example, assuming that a specified region of a vessel has an internal volume of 20 ml over a defined axial length. The device of the invention can be used to insert predetermined volumes of solution greater than, less than, or equal to 20 mls over the defined length of the vessel. Depending on the clinical environment, the ratio may be altered to remove greater volume by establishing a smaller ratio of irrigation to aspiration. One could, for example, irrigate with one volume of solution while removing twice the volume through the aspiration portion of the system to yield a 1:2 irrigation to aspiration volume.
In a preferred embodiment, the fluid exchange device has the ability to perform a controlled exchange of fluid with predetermined ratios including a 1:1 irrigation to aspiration ratio and varying ratios particularly values ranging between a 1:2 irrigation to aspiration ratio and a 2:1 irrigation to aspiration ratio. Preferably, this is achieved by having irrigant and aspirant reservoirs of defined volumes built into the fluid exchange device. However, the device can also feature a selectable control that alters the ratio of fluid exchange between a minimum and a maximum as a function of the operation of the device. In the mechanical embodiment of the fluid exchange device, each actuation of the device may cause a defined volume of fluid to be propelled through an outlet that is in fluid communication with the irrigant lumen of a catheter element. In combination, the device also features an aspirant reservoir which is expanded by a predetermined volume relative to the volume of the irrigant that is expelled.
The control of these parameters, in some aspects, by the fluid exchange device is the result of designing the fluid exchange device to cooperate with both conventional catheters as well as those specially designed to produce turbulent flow at the target fluid exchange site. The fluid control functions of the exchange device can also cooperate with the catheter element by incorporating the capability for the fluid exchange device to control motion of the catheter, specifically axial movement within a body conduit such as a blood vessel. In this embodiment, the catheter element is coupled to the actuation of the fluid exchange device by a coupled translation mechanism wherein, as described in further detail below, each actuation of the device results in automatic advancement or retraction of the catheter. Thus, a defined exchange of fluid volume at the target site occurs in combination with advancement or retraction of the aspiration and/or irrigation element of the catheter by a defined distance. In this manner, repeated actuation of the device provides a step-wise motion of the irrigation and evacuation functions and can insure a near quantitative volume exchange over a defined distance. As will be apparent from the following description, this aspect of the invention provides the ability to insert and/or remove a defined volume of fluid distal of an occluding member given an approximate knowledge of the dimensions of the vessel. As with the other embodiments, the operation of the system may provide fluid exchange with a pulsatile fluid flow by virtue of the application and dissipation of pressure achieved through the catheter.
Any number of designs for the fluid exchange apparatus can be used to provide controlled volumes of irrigation and aspiration fluids, through the catheter element of the invention to the target exchange site. The simplest embodiment of the invention provides a squeeze bulb wherein the irrigant and aspirant reservoirs are typically separated by a membrane and are in fluid communication with a irrigation and aspiration lumen that communicate fluids to and from the target site. In this embodiment, a one-way valve is provided preferably on both the irrigant and aspirant side of the fluid flow, to prevent aspirated fluid from flowing back to the target site. In another embodiment, a mechanical device causes pressure to be exerted on an irrigant reservoir that is in fluid communication with an irrigation lumen that provides fluid flow to at least one irrigation port at the distal end of a catheter. The catheter element also comprises an aspiration lumen, that may or may not be integral with the irrigation lumen, and which facilitates fluid communication of the aspirant fluid back to an aspirant reservoir. In this embodiment, the irrigant is expelled from a reservoir by the application of mechanical force to reduce the volume of the irrigation reservoir and the mechanical force is preferably coupled to an expansion of the volume of the aspirant reservoir to yield a defined fluid exchange between the irrigant reservoir and the aspirant reservoir.
Those skilled in the art of medical devices will appreciate that all of the component parts of the invention are assembled from biocompatible materials, typically medical plastics or stainless steel. The syringes described below may be ordinary medical-use syringes or may be custom fitted to be replaceable and to fit engagingly with the fluid exchange apparatus. An irrigant reservoir that is integral with the device may be pre-filled or a pre-filled syringe may be used to supply the irrigant fluid. In either a stainless steel or plastic embodiment, the device is stabilized. Typically, stainless steel devices are exposed to heat and steam in an autoclave, while medical plastics may be exposed to gamma irradiation or microbicidal gases such as EtO. The methods of the invention specifically include the use of any component of the system of the invention followed by sterilization of the components, or the entire system, and re-packaging for subsequent use. Although plastic embodiments are designed for single use, sterilization may be performed to functionally reconstruct the utility of the device after use with a patient.
In one preferred embodiment, a hand-held mechanical device is actuated by a trigger to insert and remove controlled volumes of fluid through the catheter element. The hand-held embodiment is comprised of an actuator such as a movable trigger that is mechanically operated by being grasped by the hand and pulled towards a stationary structural housing of a complementary portion of a housing to cause a reduction in the volume of an irrigant reservoir and, accordingly, fluid movement through an irrigation lumen and out one or more irrigation ports at the distal end of a catheter. Fluid provided to the target site in this manner is recovered through one or more aspiration ports and communicated through an aspiration lumen and returned to the aspirant reservoir of the fluid exchange device. The irrigant and/or aspirant fluids are preferably contained in a sealed reservoir system such as a cylindrical chamber having a piston and a rod wherein the piston is mechanically coupled to the actuating element. Motion of the actuating element transfers force to the piston and causes contraction of the irrigant reservoir and expulsion of liquid from the reservoir. Simultaneously, the motion of the actuator causes the expansion of the volume of the aspirant reservoir and causes withdrawal of fluid through the aspiration lumen and into an aspirant reservoir. In such an embodiment, the actuation of the trigger may translate into varying amounts of fluid flow depending on the mechanical expedients used. A single actuation of the trigger may translate into an incremental movement of a piston that exerts force on an irrigant and/or aspirant reservoir. By the use of several conventional mechanical apparatus, such as a ratchet and gear mechanism, a lever and pivot system, or others, the mechanical fluid exchange device exerts a direct control over the exchange of fluid communicated through the irrigation and aspiration lumens. The control of the fluid and the particular features can be provided in several designs that achieve the same function. For example, in addition to the hand-held apparatus described below, the force needed to create the fluid flow in both the aspiration and irrigation sides of the system could be provided by a mechanical foot pump, vacuum pump or virtually any component device that provides controllable fluid flow. Moreover, to provide total reproducibility in the operation of the system, a console controlled by a computer with appropriate commands or a software program is readily used to produce the same fluid flows, fluid exchange parameters, including exchange ratios, and essentially all of the functions of the purely mechanical embodiments described below. Therefore, those of ordinary skill in the art will appreciate that any number of mechanical or electrical variations give rise to the same fundamental principle wherein controlled volumes are applied to a target site through a segregated irrigation and aspiration system, preferably comprised of irrigation and aspiration lumens that pass through at least one catheter element and engage in fluid exchange at a target exchange site by virtue of specially designed irrigation and aspiration ports at the distal end of the catheter element.
By altering the dimensions of the irrigation reservoir and the aspiration reservoir, the ratio of fluid exchange between the irrigant and aspirant reservoirs is altered and, accordingly, the fluid exchange in the target vessel is adjusted. For example, where the irrigant reservoir and aspirant reservoir are of identical sizes, an actuation of the fluid exchange device may yield a 1:1 fluid exchange within the target vessel. Where, as described above, a different fluid exchange ratio is desired, the difference in the ratio may be achieved by a corresponding difference in the dimensions of the irrigant and aspirant reservoirs that are emptied and filled through the operation of the fluid exchange device. Also, variations in ratio may be accomplished by corresponding changes in the dimensions of in-line chambers as described below. Likewise, with a 1:1 ratio, equal volumes of irrigant and aspirant are exchanged in a single cycle of the fluid exchange apparatus. In the 1:1 embodiment, the entire irrigation and aspiration volumes may be exchanged within a defined number of cycles of the apparatus. For example, one may provide that each cycle of the hand-held apparatus provides 1 ml of irrigant volume and removes 1 ml of aspirant volume. By providing an irrigation and aspiration reservoir with known volumes, a known number of cycles translates into a known volume of irrigation and aspiration. As noted above, in one specific embodiment, the actuation of the device also causes translation of the infusion catheter along a defined axial path such that a known volume of solution is provided in both the irrigation and aspiration aspects as a function of the distance that is traveled by the infusion catheter.
Clearly, the irrigation reservoir may advantageously be divided into subparts and is not limited to ordinary aqueous solutions used in a surgical context. Given the utility of the present device for diagnostic and imaging applications, the irrigation reservoir could be filled with dyes, contrast agents, or other solutions that aid in the diagnosis or treatment of the vessel. Given that the fluid exchange device of the invention also provides unique fluid flow parameters, the irrigation reservoir could contain therapeutically valuable solutions such as heparinized ringers lactate, streptokinase, urokinase, tissue plasminogen activator, or other thrombus or emboli treatment fluids that are used to perform the therapeutic procedure on the internal portion of a vessel or organ. Given the ability to specifically tailor the fluid exchange parameters for a target vessel, the device offers the ability to use therapeutic compounds that might not otherwise be available because the clinician can be certain of the enhanced ability to remove solutions introduced via the irrigation reservoir. The fluid exchange apparatus can also be used to promote absorption of a therapeutic layer on a vessel wall. If a drug coated stent is produced that can reabsorb drugs after they have eluted, then with this device a high concentration of the drug can be introduced and pooled about the stent for a brief period. This high dose may then be absorbed or bonded back to the structure or one of its components and thereby recharging the drug coated stent.
Finally, in a system where it may be advantageous to have ratios other than 1:1 in the system it is also directly applicable. For example, in another vascular situation a virtual shunt may be created where a proximal fluid can be circulating and a fluid is infused distally. This would involve a ratio of greater than 1:1 irrigation to aspiration. Furthermore such an arrangement could introduce a second fluid to be the primarily distally delivered fluid. The second fluid could be blood, blood substitute, plasma or oxygenated fluid to produce a virtual shunt.
In the diagnostic use of optical coherence tomography, OCT, the fields of applications are presently limited by the need for a clear field. Similarly the use of intravascular ultrasound, IVUS, is somewhat limited by the attenuation associated with the blood in vivo. A substantial volume exchange of the vessel region in proximity of the distal end of the OCT or IVUS catheter would provide the opportunity to replace blood or other fluids with transparencies other than that found in blood, thus improving and/or modifying the imaging quality.

Fluid exchange system for controlled and localized irrigation and aspiration


Hot-pumpable, heat-curing compositions based on solid ethylene/vinyl acetate copolymers and liquid reactive plasticizers containing olefinically unsaturated double bonds and at least one peroxidic crosslinking agent are suitable as sealing compounds for sealing fine and rough seams in vehicle manufacture. By adding expanding agents, the compositions may be used as lining adhesives. The preferred applications are at the white-shell stage of car manufacture.

1. Field of the Invention
This invention relates to hot-pumpable, heat-curing compositions based on ethylene/vinyl acetate copolymers (EVA), to their use as sealing compounds or lining adhesives, to a process for sealing seams in vehicle manufacture and to a process for lining sandwich components in vehicle manufacture.
2. Discussion of Related Art
In machine construction, vehicle construction or equipment manufacture and particularly in car manufacture, the metal components are, for the most part, still mechanically assembled and fixed at the so-called white-shell stage. Conventional fixing methods include riveting, screwing or welding, particularly spot welding, and flanging processes. The seams between the parts thus joined have to be sealed against penetrating water, dust and the like. Conventional compounds for sealing these seams are based either on plastisols or on rubber compositions. In car manufacture, sealing is increasingly being carried out at the so-called white-shell stage for manufacturing reasons, i.e. the sealing compounds are generally applied to the uncleaned metal surface. The surfaces are often coated with various corrosion inhibiting oils or drawing oils so that the sealing compounds used thereon should not be functionally affected by these oils. The sealants are cured at a later stage in the paint drying ovens. Before curing, the joined and sealed parts pass through cleaning, phosphating and dip-priming stages. The treatment compositions used in those stages are capable of flushing the sealants from the joints. For this reason, all sealants or sealing compounds or adhesives used at the white-shell stage of vehicle manufacture are required to be resistant to washing. Hitherto, these requirements have been satisfied by various procedures including, for example, thermal/inductive precuring or pregelation of low-viscosity paste-form adhesives/sealants or sealing compositions based on plastisols. These plastisols may be PVP plastisols of the type described, for example, in DE-A-1769325 or in DE-A-2200022, although (meth)acrylate plastisols of the type described, for example, in DE-A-2454235 or DE-A-3523480 may also be used. The styrene-copolymer-based plastisols disclosed in DE-A4034725 and in DE-A-4315191 are also mentioned in this regard. Separate equipment is required for the precuring or pregelation step necessitated by the use of plastisols. In general, the equipment in question consists of special induction heaters or hot-air or infrared heaters. Besides the additional investment involved, this procedure has another disadvantage. On account of the short cycle times, the pregelation step has to be carried out by so-called heat shock so that the surfaces of the metal parts briefly assume very high temperatures. This can lead to cracking of the corrosion-inhibiting and drawing oils applied to the metal surfaces.
Rubberbased sealants and sealing compounds which are applied hot are also known. After cooling to ambient temperature, these compounds/compositions have such a high intrinsic viscosity that they are resistant to washing a few minutes after application. Hot-applied rubber compositions are widely used as adhesives, sealants and sealing compounds at the white-shell stage of car manufacture. These compositions contain rubbers, more particularly vulcanizable rubbers based on 1,4-polybutadienes and/or 1,4-polyisoprenes. The compositions preferably contain liquid polydienes of low molecular weight, sulfur and optionally accelerators for sulfur vulcanization. The compositions may additionally contain high molecular weight, so-called solid rubber, both the liquid polydienes and the solid rubber optionally containing functional groups such as, for example, hydroxyl groups, carboxyl groups, anhydride groups or epoxy groups. The use of these rubber compositions as adhesives/sealants is the subject of a number of patent applications, cf. for example EP-A-97394, EP-A-309903, EP-A-309904, DE-A-3834818, DE-A-4120502, DE-A-4122849 and EP-A-356715. Unfortunately, the rubber compositions in question have a very tacky surface and can very easily be deformed by mechanical pressure before they are cured in the paint drying ovens. This is a major disadvantage above all where they are used for fitted parts, such as for example doors, bonnets or boot lids, because such parts often have to be stacked and stored during the manufacturing process. The tacky surface binds very large quantities of dust and soil and the fact that the rubber compositions can easily be mechanically deformed often leads to handling marks on the visible part of seams in particular so that the appearance of the sealed joint is adversely affected.
Attempts have been made to solve some of the problems mentioned above by using two-component rubber systems. Thus, EP-A-181441 describes a two-component system consisting of a hydroxyfunctional 1,3-polybutadiene and a second component which consists of a polymer based on 1,3-butadiene and which contains lateral succinic anhydride groups. EP-A-356715 describes a two-component system consisting of a polymer A containing at least two hydroxyl groups per macromolecule and of a second component which is compatible with component A and which contains on average at least two carboxyl groups or carboxylic anhydride groups per molecule. Through the use of suitable catalysts, these two-component materials can develop a certain strength at room temperature through the esterification reaction alone. Ultimate strength is developed by an additionally incorporated sulfur vulcanization system during vulcanization in the paint drying ovens. However, these two-component systems only develop adequate resistance to pressure and handling about 30 minutes after application. This means that the corresponding parts can only be further processed some 30 minutes after application of the two-component system. In addition, two-component systems, particularly those of high viscosity, require elaborate metering and mixing units to be able to guarantee a reasonably dependable level of process safety.
Although conventional hotmelt adhesive compositionsxe2x80x94through their rapid build up of strength after coolingxe2x80x94would enable corresponding sealing compounds rapidly to develop resistance to pressure and handling, these hotmelt adhesives have two major disadvantages:
they require very high application temperatures
on account of their thermoplastic character, they soften and flow at the temperatures prevailing in the paint drying ovens so that they would flow out from the joint.
Accordingly, the problem addressed by the present invention was to provide hot-pumpable heat-curing compositions which could be directly applied to uncleaned surfaces at the white-shell stage of car manufacture and which, when used as sealing compounds, would have adequate resistance to pressure and handling only a short time after application so that the corresponding parts could be immediately further processed. In addition, these sealing compounds would have a tack-free surface so that they would not attract dust or soil. In addition, a tack-free surface of the sealing compounds would ensure that machinery and equipment in which car parts thus sealed are further processed would not be contaminated by the sealing compounds. In addition, the binder system would be formulated in such a way that curing or crosslinking of the sealing compound could take place even over the broad temperature ranges encountered in the stoving phase of electrophoretic coating in car manufacture. In addition, it would have to be guaranteed that the cured sealing compound would have an attractive smooth surface because the corresponding joints are often visible. For reasons of corrosion control, no pores or open bubbles should occur. In addition, the surfaces would be required to lend themselves to coating with conventional automotive lacquers.
The solution to the problem stated above is defined in the claims and lies essentially in the use of heat-curing compositions containing at least one solid ethylene/vinyl acetate copolymer (EVA copolymer) with a softening point above 50xc2x0 C., as measured by the ring and ball method according to ASTM-E-28, at least one liquid reactive plasticizer containing olefinically unsaturated double bonds and at least one peroxidic crosslinking agent.
Although the use of plasticizers in peroxide-containing ethylene/vinyl acetate copolymer compositions is known in principle, manufacturers of EVA copolymers point out that only high saturated products are suitable for this purpose because they have no effect on peroxide vulcanization. According to the manufacturers, paraffinic mineral oils with very little unsaturation (olefinic double bonds) are particularly suitable as plasticizers. In addition, adipate and sebacate plasticizers, for example adipic acid benzyl octyl ester (Adimoll BO) and alkyl sulfonic acid esters of phenol (Mesamoll), are also specifically recommended.
To obtain the character of a hotmelt adhesive, the sealing compounds according to the invention contain EVA copolymers which are solid at room temperature, i.e. they must have a softening point of 50xc2x0 C. as measured by the ring and ball method according to ASTM-E-28. The EVA copolymers are used in quantities of 4 to 40% by weight and preferably 7 to 33% by weight in the sealing compounds according to the invention.
In order to make the sealing compounds hot-pumpable with the applicators typically used in car manufacture and at the necessary pressures, the EVA copolymers have to be plasticized. The expression xe2x80x9chot-pumpablexe2x80x9d in the context of the present invention is intended to mean that the sealing compounds have a sufficiently low viscosity at temperatures of 60 to 110xc2x0 C. and preferably at temperatures of 70 to 100xc2x0 C. to be able to be processed with the usual pumps, feed systems and applicators.
Liquid rubbers from the following group of homopolymers and/or copolymers may be used as liquid reactive plasticizers containing olefinically unsaturated double bonds: polybutadienes, more particularly 1,4-, 1,3- and 1,2-polybutadiene, polyisoprenes, styrene/butadiene copolymers and butadiene/acrylonitrile copolymers, these polymers preferably at least partly containing terminal and/or (statistically distributed) lateral functional groups. Examples of such functional groups are hydroxy, carboxyl, carboxylic anhydride, epoxy or amino groups. The molecular weight of these liquid diene homopolymers and/or copolymers is typically below 20,000 and preferably between 1,000 and 10,000. The liquid rubbers are present in the compositions according to the invention in quantities of 5 to 40% by weight and preferably in quantities of 14 to 35% by weight. The rheology of the compositions as a whole is influenced to a large extent by the ratio of liquid rubbers to EVA copolymers, so that the flow behavior of the compositions can be varied within wide limits through that ratio. Accordingly, it is possible to produce both extrudable and sprayable sealing compounds.
In addition to the polydienes mentioned above, other compounds containing olefinically unsaturated double bonds may also be used and include, in particular, high-boiling (meth)acrylates, more particularly pentyl (meth)acrylate, isoamyl (meth)acrylate, hexyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate and the corresponding octyl, 3,5,5-trimethyl hexyl, decyl, dodecyl, hexadecyl, octadecyl and octadecenyl (meth)acrylates and the corresponding esters of maleic, fumaric, tetrahydrophthalic, crotonic, isocrotonic, vinyl acetic and itaconic acid. (Meth)acrylates containing more than one double bond per molecule are preferably used. Examples of such (meth)acrylates are ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, trimethylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,3-butylene glycol di(meth)acrylate, 1,4-butylene glycol di(meth)acrylate, 1,6-hexamethylene glycol di(meth)acrylate, 1,10-decamethylene glycol di(meth)acrylate, trimethylol propane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate or pentaerythritol tri(meth)acrylate. The acrylic and methacrylic acid salts of divalent metals are also suitable. Examples include the corresponding zinc diacrylates and zinc dimethacrylates. The reactive (meth)acrylate compounds mentioned above are used in quantities of 1 to 10% by weight and preferably in quantities of 3 to 6% by weight.
The following factors are important as selection criteria for the peroxidic crosslinking agents:
the peroxides must have sufficient stability under pumping conditions, i.e. at temperatures of about 70 to 120xc2x0 C., to ensure that no significant curing reaction takes place under such temperature and application conditions,
at the temperatures prevailing in the stoving phase of electrophoretic coating, i.e. at temperatures of 160 to 240xc2x0 C., the decomposition rate of the peroxides must be sufficiently rapid to guarantee crosslinking of the sealing compound in 15 to 30 minutes (residence time in the stoving oven).
Examples of suitable peroxides are tert.butyl cumyl peroxide, di-(2-tert.butylperoxypropyl)-(2)-benzene, dicumyl peroxide, ethyl-3,3-di(tert.butylperoxy)-butyrate, n-butyl-4,4xe2x80x2-di-(tert.butylperoxy)-valerate, tert.butylperoxy benzoate, tert.butyl hydroperoxide, cumene hydroperoxide, 1,1,3,3-tetramethyl butyl hydroperoxide and 2,5-dimethyl-2,5-di-(tert.butylperoxy-hexine)-3.
The quantities in which the peroxides are used are governed by the criteria mentioned above and are between 0.1 and 5% by weight and preferably between 0.5 and 1.5% by weight.
In addition, the compositions according to the invention may contain so-called kickers or activators which accelerate peroxide crosslinking, for example aromatic amines and metal oxides, such as zinc oxide. Where activators are used, they are employed in quantities of up to 6% by weight and preferably 2 to 4% by weight.
Conventional stabilizers may be used to protect the compositions according to the invention against thermal, thermo-oxidative, ozone or hydrolytic degradation. Examples of conventional stabilizers are the sterically hindered phenols or amine derivatives and, more particularly, carbodiimide stabilizers and polycarbodiimide derivatives which are preferably used in the form of a master batch in an EVA copolymer. The stabilizers in question are used in quantities of up to 5% by weight and preferably in quantities of 1 to 3% by weight.
The fillers may be selected from various materials including, in particular, chalks, natural or ground calcium carbonates, silicates, more particularly aluminium silicates or magnesium aluminium silicates or magnesium alkali metal aluminium silicates, or even talcum or graphite or carbon black. The quantity in which the fillers are used may vary within wide limits, typical ranges being from 20 to 70% by weight and preferably from 40 to 50% by weight. To produce sealing materials of low specific gravity, the fillers may also be partly replaced by hollow plastic microbeads which may be used either in pre-expanded form or in the compact form in which they only expand during curing of the sealing compound in the paint drying oven. Hollow microbeads of the type in question are disclosed, for example, in EP-A-586541 and in U.S. Pat. No. 4,829,094.
In addition, the compositions according to the invention may contain pigments, for example titanium dioxide, iron oxides or pigment-quality carbon blacks. The pigments mentioned are used in the formulation in quantities of up to 5% by weight and preferably in quantities of 1 to 3% by weight. To reduce sensitivity to moisture, it may be advisable to incorporate water-binding agents, more particularly calcium oxide, in the formulations in quantities of 1 to 10% by weight. Quantities of 3 to 5% by weight of calcium oxide are preferably used.
To improve coating of the sealing compounds with paints applied by electrophoretic deposition, the compositions may contain graphite in known manner in quantities of 5 to 15% by weight and preferably in quantities of 25 to 35% by weight instead of the pigments and fillers mentioned.
Where the compositions according to the invention are used as a lining adhesive for lining sandwich parts, they may also contain expanding agents from the class of azo compounds, N-nitroso compounds, sulfonyl hydrazides or sulfonyl semicarbazides. Azo-bis-isobutyronitrile and, in particular, azodicarbonamide are mentioned as examples of azo compounds suitable for use in accordance with the invention. Dinitrosopentamethylene tetramine is mentioned as an example of a suitable nitroso compound, 4,4xe2x80x2-hydroxy-bis-(benzenesulfonic acid hydrazide), diphenyl sulfone-3,3xe2x80x2-disulfohydrazide and benzene-1,3-disulfohydrazide are mentioned as examples of sulfohydrazides and p-toluene sulfonyl semicarbazide is mentioned as an example of a semicarbazide. Instead of the expanding agents mentioned above, however, it is also possible to use non-expanded hollow microbeads which, in their non-expanded form, are known to consist of thermoplastic polymer powders impregnated or filled with low-boiling organic liquids. For use as a lining adhesive, these compositions should expand by about 20% to about 250% in volume during curing. Potential applications for such lining adhesives are the following sandwich structures in car manufacture: roof bows with an outer roof skin, bonnet or boot lids with reinforcing frames, steel sliding roofs with reinforcing frames, inner door and outer door panels, window channel reinforcement with outer door panels, side impact crash bars against outer door panels. Expansion of the lining adhesive ensures that, despite the thermal expansion of the panels or in the event of movement of the panels under the effect of heat in the paint drying oven and despite manufacturing tolerances, wetting of the second substrate with the lining adhesive is guaranteed. The expanding agents mentioned above are used in quantities of up to 3% by weight and preferably in quantities of 0.5 to 1.5% by weight.
Depending on the substrate to be sealed, it may be necessary to use adhesion promoters or tackifying resins known per se in the composition according to the invention. Suitable adhesion promoters or tackifiers are mentioned, for example, in DE-A-19644855, pages 8/9. They may be used in quantities of up to 10% by weight and preferably in quantities of 3 to 5% by weight.
The following Examples are intended to illustrate the invention without limiting its scope in any way.

Hot-setting wash-fast sealant for shell structures


An automated carrier-based pest control system is provided, and includes a substantially automated sprayer. The system also includes a container in fluid communication with the substantially automated sprayer for holding a mixture of carrier-based ingredients, including one or more ingredients, for discharge from the substantially automated sprayer. Also includes is one or more discharge control units operably connectable to the substantially automated sprayer and to the container for regulating discharge of the mixture of carrier-based ingredients.

The present invention pertains generally to controlling pests on an animal. More particularly, the present invention pertains to a substantially fully automated system for applying carrier-based mixture containing one or more pesticides to bovines. The present invention is particularly, but not exclusively, useful for variably discharging carrier-based mixtures on cows in a dairy herd.
Control and management of pests has proven challenging, costly, illusive, and frequently ineffective. Pests of concern to dairy herdsman include (i) not only the conventional class of arthropods and related classes and orders known as muscoid and nonmuscoid flies, but also (ii) arachnids, a class of mainly terrestrial arthropods comprising spiders, scorpions, mites, ticks, and the like, (iii) ectoparasites, which are parasites living on the surface of an animal, and (iv) endoparasites, parasites living within an animal. Muscoid and nonmuscoid flies, for example, in a wide variety of species, cluster synanthropically to humans and their domestic animals, or in close proximity to humans and domesticated animals such as cows.
Pests are of concern because of their dramatic impact on the economics of animal production, a commercial industry constituting a significant contribution to the gross national product of the United States. The dairy cattle industry has been estimated to produce $12 billion annually. The several different species and classes of flies commonly found on livestock and livestock premises may cause a number of problems, including irritating cows so severely that milk production suffers; transmitting disease pathogens; increasing enteric (intestinal) diseases among humans associated with cow herds; violating regulatory rules and regulations, and generating a host of related problems.
A variety of devices, apparatus and methods have been proposed for controlling pests among cattle, including dairy cows. Except for the invention disclosed in U.S. Pat. No. 6,230,660 B1, issued May 15, 2001 to the sole inventor named in this application, and in the co-pending and allowed application cross-referenced in this document, (xe2x80x9cPrior Inventionsxe2x80x9d), none has proven effective in achieving the level of control demanded by industry operators, or providing substantially automated control of pest populations. No other solutions provide apparatus and methods for varying the rate and amount of discharge of ingredients used to combat pests, particularly the rate and amount of chemical discharge, to reduce costs while maintaining pest control on and around animals.
Known proposals for controlling flies attracted to cattle include burying parasites in soil beneath the surface of the soil on which cattle are penned. Other pests, including nematodes, have been introduced into herd locations in hopes of fly control. Flytraps using bait attractants have been used. Those techniques have proven ineffective in controlling fly populations attracted to cattle pens. Parasites achieve control of only a small portion of a fly population, and then only temporarily. Parasites reproduce more slowly than the rate at which flies reproduce, and their hatch rates are unreliable and unpredictable. An effective parasite population also may be reduced because parasites die or fly way. Use of parasites as a method for attempting to control flies among cattle is labor intensive, therefore expensive, usually making the solution unacceptable to an operator of a cattle business. Virtually no control is achieved using nematodes. Nematodes are not suitable for use in acidic soils. Because of the large amounts of manure and urine produced by multiple pens of cattle, all soil used for cattle becomes acidic. In addition, use of nematodes is impractical because nematodes must be applied or introduced into a herd at night, only after rainfall, and reintroduced frequently to achieve any measure of success in controlling pests on an animal and animal herd. No marked reduction of a pest population occurs with use of fly traps. Flytraps, for example, rely on bait. No bait, however, has proven effective for flies, particularly on large tracts of land used to pen large cattle herds.
Spraying or fogging chemicals on cattle has proven marginal in achieving control of flies for long periods of time. Fogging causes droplet drift, so fogging is not cost effective. For similar reasons, aerial spraying has proven no more effective than use of fly parasites, nematodes, and fly traps using bait attractants.
Other proposals for controlling pests among cattle include feeding cows oral larvicide and applying residual pesticides on the underside of shaders. No significant long-term reduction in the fly population has been observed using an oral larvicide, primarily because no chemical that might work effectively against flies may be fed orally to milking cattle. Even more primitive devices have been used, such as back rubbers, both manuals and automated. A manual back rubber applicator requires an operator to periodically remove, dip into a chemical, and reinstall a rubber device above the back of a cow that walks beneath the rubber device. No noticeable difference, however, in fly population has been observed using this method, and automated variations have proven no more effective. Ear tags, or other apparatus attachable to parts of an animal""s body, containing a liquid chemical or pesticide dispensable on an animal, also have not satisfied the industry requirements for an apparatus that provides substantially complete control of the fly population in the form of a substantially automated system requiring relatively little attention during operation. Ear tags or similar apparatus connectable to parts of an animal body cannot be designed to release or apply sufficient chemicals either to an animal or to flies.
Attempting to control pests by spraying underneath shaders, direct spraying of roosting flies, and spraying vegetation near cattle pens, also are ineffective. Those techniques may eliminate problems associated with food and water contamination, but are labor intensive and expensive. An average dairy herd, for example, requires six to seven hours to complete one such spraying cycle, a cycle that must be repeated often to achieve even minimal control. A problem encountered by these methods is the tendency of flies to change roosting areas regularly, requiring an operator to hunt fly roosting areas to effectively induce a spray.
Larvicide spraying has not proven feasible because of the huge volume of water required to penetrate at least three inches below the surface of soil where fly larvae feed. The typical service truck carries only 500 gallons of water, and for a cattle herd held in a common arrangement of twelve pens, the cost of frequent larvicide applications is prohibitive.
As the inventor named in this document has disclosed in prior applications and patents, a mixture that includes at least one chemical and at least one oil, although expensive, has proven the most effective combination of ingredients to control pests among bovines, particularly in dairy environments. As used in this document, the term xe2x80x9ccarrier-based chemical mixturexe2x80x9d or xe2x80x9cmixture of carrier-based ingredientsxe2x80x9d includes a wide variety of carriers such as oil, silicon, polymers, gels, and thickening agents that are chemically inert and that are useful in connection with the present invention. Also as used in this document, the term xe2x80x9cchemicalxe2x80x9d includes, as non-exclusive examples, pyrethroids, organopolysiloxanes, organophosphates, and systemic endoparisites, among others. Accordingly, it would be of considerable advantage to provide an automated carrier-based pest control system for applying a mixture of carrier-based ingredients on bovines assembled in herds.
The present invention provides important advantages over present technology. At least one advantage of the present invention is the capability for variably discharging ingredients on an animal. The term xe2x80x9cvariably discharging,xe2x80x9d and equivalent forms used in this document include discharge of a mixture of carrier-based ingredients at different times, in differing rates, in different amounts, in varying spray patterns, either continuously, or in one or more interrupted sequences. The term xe2x80x9cdifferent spray patternsxe2x80x9d includes at least the conventional substantially funnel-shaped spray pattern associated with nozzles, as well as a substantially focused stream or jet of a mixture of carrier-based ingredients. The term xe2x80x9cvariably dischargingxe2x80x9d also contemplates random discharges from the system. These features of the present invention significantly reduce waste of expensive chemicals, and consequently the cost of pest control, while achieving substantially full control of pests. Environmental hazards are substantially reduced. The apparatus of the present invention is so efficient that little chemical is wasted, thus affording the user a significant chemical cost reduction.
Accordingly, at least one object of the present invention is to provide an automated carrier-based pest control system for applying a mixture of carrier-based ingredients on bovines assembled in herds. Such a system, preferably in a permanent installation for controlling pests on cattle, allows regular, repetitive, effective and thorough application of the best and most appropriate combination of ingredients, including carrier-based chemical mixtures, while substantially eliminating user involvement during operation of the apparatus.
Another object of the present invention is the use of a variety of sensors, including units that include sensors in combination with counters and other devices for applying carrier-based ingredients on bovines. The sensors may include diffused deflective infrared sensors, which also may be used with a plurality of pulse/speed indicators, to cooperate in discharging ingredients based on the rate of movement of the animal.
Still another object and advantage of the present invention is the inclusion of one or more sensors operatively connectable to the discharging means for regulating discharge of the carrier-based mixture of chemicals consistent with, and as a function of, the speed of the animal.
Another object and advantage of the present invention includes a pest control apparatus that includes one or more sensors that can control discharge of the carrier-based mixture of ingredients regardless of the location of the animal in relationship to the sprayer.
Yet another object and advantage of the present invention is responsive to the fact that insects may not cluster or be distributed uniformly or homogeneously on an animal""s body considered as a whole. Rather, insects may cluster on one or more locations on an animal. For example, insects may mass along the back of a cow, on the head of a cow, or on the stomach of a cow. It is therefore an object of the present invention to provide means for varying not only the configuration of the sprayed discharge of the carrier-based mixture of chemicals from the apparatus, but also the locations on the animal anatomy that the discharged mixture may be directed in varying amounts.
Another object and advantage of the present invention is an automated carrier-based pest control system for applying a mixture of carrier-based ingredients on bovines assembled in herds that respectively are easy to use and to practice, and which are cost effective for their intended purposes.
These and other advantages are achieved in the present invention by providing an automated carrier-based pest control system for applying a mixture of carrier-based ingredients on bovines assembled in herds in which the ingredients are dischargeable through one or more regulated and adjustable nozzles that may be attached to a unitary sprayer, or mounted on a gate or dividing bar used to temporarily inhibit passage of cattle through a permanent installation for controlling pests in a herd. Nozzle flow is adjustable and may be regulated, using a valve, solenoid, or mechanical means to adjust the configuration of the spray. As indicated, an animal""s presence, location, and movement may be monitored by not only a sensor, but a sensor-timer combination or similar combination of sensors.
The system of the present invention also includes one or more programmable controllers for variable discharge rates from the spray apparatus on the animal, as well as a variety of timers for scheduling discharge of the ingredients at any desired time interval. The system also provides a plurality of pulse/speed devices for discharging ingredients as a function of the position of the animal in relation to the spray apparatus.
It will become apparent to one skilled in the art that the claimed subject matter as a whole, including the structure of the apparatus, and the cooperation of the elements of the apparatus, combine to result in a number of unexpected advantages and utilities. The advantages and objects of the present invention, and features of an automated carrier-based pest control system will become apparent to those skilled in the art when read in conjunction with the accompanying following description, drawing figures, and appended claims.
The foregoing has outlined broadly the more important features of the invention to better understand the detailed description that follows, and to better understand the contribution of the present invention to the art. Before explaining at least one embodiment of the invention in detail, it is to be understood from the invention is not limited in application to the details of construction, and to the arrangements of the components, provided in the following description or drawing figures. The invention is capable of other embodiments, and of being practiced and carried out in various ways. Also, the phraseology and terminology employed in this disclosure are for purpose of description, and should not be regarded as limiting.
As those skilled in the art will appreciate, the conception on which this disclosure is based readily may be used as a basis for designing other structures, methods, and systems for carrying out the purposes of the present invention. The claims, therefore, include such equivalent constructions to the extent the equivalent constructions do not depart from the spirit and scope of the present invention. Further, the abstract associated with this disclosure is neither intended to define the invention, which is measured by the claims, nor intended to be limiting as to the scope of the invention in any way.
The novel features of this invention, and the invention itself, both as to structure and operation, are best understood from the accompanying drawing, considered in connection with the accompanying description of the drawing, in which similar reference characters refer to similar parts, and in which:

Automated carrier-based pest control system